Figure 9. The differences in yaw stability at different angles of attack also depend on the presence or absence of leg feathers.

A, At 0, some feathered-leg postures are more stable in yaw than others. B, At 60, postures that were stable at 0 may go unstable, such as tent posture with leg feathers. C, At 90, all postures are marginally stable due to symmetry. Color represents the base posture: red for sprawled, blue for tent, green for biplane, and purple for down.